Well, in most European countries, it is the law. That is, every employer must prove to authorities that there is nobody with the same qualifications available within the country before offering the job to foreigners. Now, it is little different when you are talking about legal immigrants, they have the same treatment as locals.

In my opinion, the only solution for this is better control in immigration and who can get legal status. Forcing all decisions on employers will just make them always opt for the cheapest solution.

I agree with DrDarko as the employer will always choose the cheaper solution and this causes great resentment among people who have lived in a certain coun try all their lives and paid national insurance and taxes.
People talk of political correctness and being tolerant of immigrants. This would be much easier to do if they were treated as visitors to the country who have not contruibuted and therefore have to queue behind the people who have paid and contributed all their lives. That is only fair and there is no way they will be welcomed if they push infront, claim their 'human rights' and walk off with the benefits the nationals have been slaving away for.
If you want to combat intolrance and promote true multiculturism it has to be done with the utmost sensitivity to the people who were there first.
We would not welcome an intruder into our homes who sat at our table and ate all our food, helped himself to our tv and computer then said it was his human right. The same applies to the country. If we were to invite somebody to our home as a guest, give them dinner and invite them to watch our tv and let them use our computer, its an entirely different matter. We would also hope that they would treat our home with respect and say thank you.
I hope you understand the spirit of what I am trying to say. I am not racist, I am not intolerant but I do blame the recent labour government in the UK for creating despair and dislike towards the people they are trying to promote via uncontrolled
immigration.